Rearrangement, hydride abstraction, and retro ene reactions of dicarbonyl(.eta.5-cyclopentadienyl)iron vinylidene triflates

Bly, Robert S.; Raja, M.; Bly, Ruta K.

doi:10.1021/om00039a031

Cited by 16 publications

(5 citation statements)

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“…In agreement with the last, the electrophilic addition to alkynyl complexes has shown to be also a general strategy to prepare vinylidene complexes . In addition, the deoxygenation of acylmetal derivatives by treatment with (CF 3 SO 2 ) 2 O, the deprotonation of metal carbynes, the rearrangement of alkylidene metallacyclobutane species, and the reduction of allenylidene compounds should be mentioned from hydride complexes, the most favored pathway is the insertion of the triple bond of terminal alkynes into the M−H bonds to form alkenyl intermediates, which undergo α-hydrogen elimination …”

Section: Introductionmentioning

confidence: 67%

Formation of Imine−Vinylidene−Osmium(II) Derivatives by Hydrogen Transfer from Alkenyl Ligands to Azavinylidene Groups in Alkenyl−Azavinylidene−Osmium(IV) Complexes

2000

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Treatment at room temperature of the hydride-azavinylidene complexes OsHCl 2 (dNdCR 2 )-(P i Pr 3 ) 2 [CR 2 ) CMe 2 (1), C(CH 2 ) 4 CH 2 (2)] with Ag[CF 3 SO 3 ] and the subsequent addition at -25 °C of phenylacetylene to the resulting solutions affords the alkenyl-azavinylidenewhere the H β atoms of the alkenyl ligands interact with the osmium atoms to form agostic bonds. The addition at -30 °C of NaCl to tetrahydrofuran solutions of 3 and 4 produces the split of the agostic interactions and the formation of the neutral six-coordinate alkenyl-azavinylidene compounds Os{(E)-CHdCHPh}Cl 2 (dNdCR 2 )(P i Pr 3 ) 2 [CR 2 ) CMe 2(5), C(CH 2 ) 4 CH 2 (6)]. In dichloromethane at room temperature complexes 5 and 6 evolve into the imine-vinylidene derivatives OsCl 2 (dCdCHPh)(NHdCR 2 )as a result of the hydrogen transfer from the styryl ligands to the azavinylidene groups. The structure of 7 in the solid state has been determined by an X-ray diffraction study. The geometry around the metal center could be described as a distorted octahedron with the imine group disposed trans to a chlorine atom and cis to the other one. The N-H hydrogen atom of the imine interacts with the latter to form an intramolecular N-H‚‚‚Cl hydrogen bond, which is manifested by a short Cl‚‚‚‚H separation of 2.366 Å and a Cl-Os-N angle of 77.34(18)°, largely deviated from the ideal value of 90°. Complexes 3 and 4 also react with water at -20 °C to give the cationic imine-vinylidene derivatives [OsCl(dCdCHPh)(NHdCR 2 )(H 2 O)(P i Pr 3 ) 2 ][CF 3 SO 3 ] [CR 2 ) CMe 2 (9), C(CH 2 ) 4 CH 2 (10)]. The structure of 9 in the solid state has been also determined by an X-ray diffraction study. The geometry around the metal center is octahedral with the imine group disposed trans to chlorine atom and cis to the water molecule. In this case the N-H hydrogen atom of the imine interacts with the oxygen atom of water molecule. The N-H‚‚‚O hydrogen bond is manifested by an O‚‚‚H separation of 2.36 Å and a N-Os-O angle of 78.3(2)°. The formation of 9 and 10 proceeds via the cationic six-coordinate alkenyl-azavinylidene-osmium(IV)which have been characterized in solution at -90 °C by 1 H and 31 P{ 1 H} NMR spectroscopy. Complexes 3 and 4 react with acetonitrile to give [OsCl(dCdCHPh)-(NHdCR 2 )(CH 3 CN)(P i Pr 3 ) 2 ][CF 3 SO 3 ] [CR 2 ) CMe 2 (13), C(CH 2 ) 4 CH 2 (14)] via the intermediates [Os{(E)-CHdCHPh}Cl(dNdCR 2 )(CH 3 CN)(P i Pr 3 ) 2 [CF 3 SO 3 ] [CR 2 ) CMe 2 (15), C-(CH 2 ) 4 CH 2 (16)].

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Section: Introductionmentioning

confidence: 67%

Formation of Imine−Vinylidene−Osmium(II) Derivatives by Hydrogen Transfer from Alkenyl Ligands to Azavinylidene Groups in Alkenyl−Azavinylidene−Osmium(IV) Complexes

2000

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“…In this context, it should be mentioned that although transition-metal vinylidene compounds are considered the central point of important selective transformations of alkynes with atom economy, few disubstituted vinylidene derivatives have been isolated in comparison to the large family of reported monosubstituted vinylidene compounds . The main routes previously described to prepare disubstituted vinylidene complexes involve electrophilic addition to alkynyl precursors, deoxygenation of acylmetal derivatives by treatment with (CF 3 SO 2 ) 2 O, and rearrangement of alkylidene metallacyclobutene species …”

Section: Resultsmentioning

confidence: 99%

Regioselective Addition of Dienes to the C_β−C_γ Double Bond of the Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PⁱPr₃)]BF₄

et al. 2002

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The C β -C γ bond of the allenylidene ligand of [Ru(η 5 -C 5 H 5 )(dCdCdCPh 2 )(CO)(P i Pr 3 )]BF 4 (1) adds dienes such as isoprene, cyclopentadiene, and 1,3-cyclohexadiene. The reaction with isoprene selectively affords the disubstituted vinylidene derivative [Ru(η 5 -C 5 H 5 )(dCdCCH 2 C-(CH 3 )dCHCH 2 CPh 2 )(CO)(P i Pr 3 )]BF 4 (2), whereas in the presence of cyclopentadiene a 1: 4) is obtained. In contrast to the addition of cyclopentadiene, the reaction with 1,3-cyclohexadiene is diastereoselective and gives only the racemicCH 2 C b HCHdCH)(CO)(P i Pr 3 )]BF 4 (5). The structures of 2, 3, and 5 have been determined by X-ray diffraction analysis. In the three cases, the geometry around the ruthenium center is close to octahedral, with the cyclopentadienyl ligand occupying one face.

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“…These results indicate that the more electron-rich the metal center, the more stable is the vinylidene complex, consistent with the experimental evidences; while most alkyne complexes rearrange to stable vinylidenes, the highly electron-poor cationic iron dicarbonyl vinylidene complex [( 5 -C 5 H 5 )Fe(CO) 2 (CCRR′)] + readily isomerizes to the corresponding alkyne complex [( 5 -C 5 H 5 )Fe(CO) 2 (HCCH)] + . 30 Such an effect has been attributed to: (i) the better -accepting properties of the vinylidene vis-à-vis the alkyne moiety leading to better stabilization of the vinylidene complexes by electron-rich metal fragments; and (ii) the presence in the  2 -alkyne complexes of repulsive interactions between the filled metal d orbitals and the alkyne filled  ⊥ orbital leading to a major destabilization of the alkyne complexes by electron-rich metal fragments. Notably, a tuning of the electronrichness of the metal fragment will therefore allow a control of the direction of the alkyne-vinylidene tautomerization process.…”

Section: Electron-richnessmentioning

confidence: 99%

Acetylene to vinylidene rearrangements on electron rich d6 metal centers: a density functional study

Angelis

Sgamellotti

2004

Dalton Trans.

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The acetylene to vinylidene isomerization on several Ru(II) d(6) metal fragments with different electron richness of the metal center has been investigated by means of density functional theory calculations. We considered the [(eta(5)-C(5)Me(5))Ru(dippe)](+), [(eta(5)-C(5)Me(5))Ru(dmpe)](+), [(eta(5)-C(5)H(5))Ru(PMe(3))(2)](+), [(eta(6)-C(6)Me(6))(PMe(3))ClRu](+), [(eta(5)-C(5)H(5))Ru(CO)(PPh(3))](+) and [eta(6)-C(6)H(6))(PMe(3))ClRu](+), species which are quite common in the chemistry of cationic Ru(II) complexes and span a wide range of electron-richness. For each of the considered fragments, the minima on the potential energy surfaces for the two possible isomerization mechanisms, i.e. through a direct 1,2-hydrogen shift or through a hydrido-alkynyl intermediate, have been localized. A linear correlation has been found between the C=C stretching frequencies of the vinylidene complexes, as an estimate of the electron richness, and the stability of the corresponding hydrido-alkynyl intermediates. For the most electron-rich among the considered fragments, [(Cp*)(dippe)Ru(HCCH)](+), the hydrido-alkynyl species has been found essentially isoenergetic with the alkyne complex (only 1.9 kcal mol(-1) higher), in agreement with the experimental evidence showing for this system an equilibrium between these two species. For the same [(Cp*)(dippe)Ru](+) fragment, a detailed analysis of the reaction profiles for the two possible acetylene rearrangement pathways has been performed. Our results show that once the eta(2)-C-H coordinated acetylene intermediate is accessed, the system can easily evolve towards a hydrido-alkynyl intermediate, this process being kinetically favored with respect to the direct 1,2-shift leading to the vinylidene product.

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Rearrangement, hydride abstraction, and retro ene reactions of dicarbonyl(.eta.5-cyclopentadienyl)iron vinylidene triflates

Cited by 16 publications

References 1 publication

Formation of Imine−Vinylidene−Osmium(II) Derivatives by Hydrogen Transfer from Alkenyl Ligands to Azavinylidene Groups in Alkenyl−Azavinylidene−Osmium(IV) Complexes

Formation of Imine−Vinylidene−Osmium(II) Derivatives by Hydrogen Transfer from Alkenyl Ligands to Azavinylidene Groups in Alkenyl−Azavinylidene−Osmium(IV) Complexes

Regioselective Addition of Dienes to the C_β−C_γ Double Bond of the Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PⁱPr₃)]BF₄

Acetylene to vinylidene rearrangements on electron rich d6 metal centers: a density functional study

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Rearrangement, hydride abstraction, and retro ene reactions of dicarbonyl(.eta.5-cyclopentadienyl)iron vinylidene triflates

Cited by 16 publications

References 1 publication

Formation of Imine−Vinylidene−Osmium(II) Derivatives by Hydrogen Transfer from Alkenyl Ligands to Azavinylidene Groups in Alkenyl−Azavinylidene−Osmium(IV) Complexes

Formation of Imine−Vinylidene−Osmium(II) Derivatives by Hydrogen Transfer from Alkenyl Ligands to Azavinylidene Groups in Alkenyl−Azavinylidene−Osmium(IV) Complexes

Regioselective Addition of Dienes to the Cβ−Cγ Double Bond of the Allenylidene Ligand of [Ru(η5-C5H5)(CCCPh2)(CO)(PiPr3)]BF4

Acetylene to vinylidene rearrangements on electron rich d6 metal centers: a density functional study

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Regioselective Addition of Dienes to the C_β−C_γ Double Bond of the Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PⁱPr₃)]BF₄